It is generally known that areas on an aircraft in flight are subject to direct lightning strike attachment. For an aircraft that has metallic exterior skin, which is made up of electrically conductive metal panels, this poses insignificant hazard. When lightning attaches to a conductive skin, the charge is usually conducted through the skin, the underlying aircraft structure and to a grounding system, via fasteners and other skin-to-structure connections, with negligible damage to the skin. However, when the aircraft skin is not electrically conductive, lightning strikes may cause significant damage including puncture of the skin. A non-electrically conductive skin cannot dissipate the electrical energy of the lightning strike and this localization of the energy may cause physical damage, such as possible puncture of the skin. Such a puncture raises a potential risk of lightning attachment to underlying aircraft systems. Such attachment may be very hazardous, depending upon which underlying system is affected.
One solution to the issue of lightning damage to nonconductive aircraft panels is to completely cover the outer surface area of each panel 10 that is vulnerable to lightning attachment with a conductive metal liner 12, as shown in FIG. 1. The panel 10 is attached to the aircraft underlying structure 15 via a series of metal fasteners 18 that are in electrical contact with the metal liner 12. Accordingly, electrical energy from the lightning strike 20 onto panel 10 is dissipated across the metal liner 12 to fasteners 18 and thence to the aircraft structure 15, as shown by arrows in FIG. 1. In order to reduce weight, the metal liner 12 may be of an expanded aluminum or other alloy. Nonetheless the use of a metal liner on each panel vulnerable to lightning strikes adds weight to the aircraft design and reduces aircraft payload.
Accordingly, there is a need for a lighter-weight lightning protection system as an alternative to the use of electrically-conductive metal liners that completely cover the entire outer surfaces of panels of aircraft that has a skin of nonconductive panels. Other desirable features and characteristics of the present invention will become apparent from the subsequent detailed description and the appended claims, taken in conjunction with the accompanying drawings and the foregoing technical field and background.